The invention relates to fire and explosion detection systems and more specifically to systems which are able to discriminate between fires and explosions which need to be detected and fires, explosions and other radiation sources which do not.
Systems to be described by way of example below, and embodying the invention, may be used, for example, in situations where it is required to discriminate between the explosion of an ammunition round itself and a fire or explosion of combustible or explosive material which is set off by that round--so as to detect the fire or explosion set off by the round but not to detect the exploding round itself. In this way, the system can initiate action so as to suppress the fire or explosion set off by the round, but does not initiate such suppression action merely in response to the exploding round.
One particular application of the systems is for use in an armoured personnel carrier or battle tank which may be attacked by high energy anti-tank (H.E.A.T.) ammunition rounds. In such an application, the system is arranged to respond to hydrocarbon fires (that is, fires involving the fuel carried by the vehicle) set off by an exploding H.E.A.T.round or set off by hot metal fragments produced from or by the round (or set off by other causes), but not to detect either the exploding H.E.A.T.round itself (even when it has passed through the vehicle's armour into the vehicle itself), or the secondary non-hydrocarbon fire which may be produced by a pyrophoric reaction of the H.E.A.T. round with the vehicle's armour.